Polyimide film excellent in alkali etching processability and punchability

Abstract

A polyimide film according to the present invention satisfies Condition (1) in which a tear propagation resistance variation C H is not more than 1.0 g, and/or Condition (2) in which a swelling coefficient C R after being dipped in an alkaline solution is not more than 20.0. By satisfying these conditions, workability of the polyimide film can be improved and working defects can be effectively prevented, thereby improving productivity of each step.

1. A polyimide film with a tear propagation resistance variation of not more than 1.0 g, comprising not less than 25 mol % of paraphenylene diamine and not less than 25 mol % of 4,4-diaminodiphenylether, both as diamine components, with respect to a total diamine component said polyimide film comprising a repeating unit of formula (1) below in its molecules 
       
         
           
           
               
               
           
         
       
       where R is 
       
         
           
           
               
               
           
         
       
       and where n of the group R is an integer of 1 to 3, X and Y are independently a hydrogen, a halogen, a carboxyl group, a lower alkyl group with no greater than 6 carbon atoms, or a lower alkoxy group with no greater than 6 carbon atoms, and A is —O—, —S—, —CO—, —SO 2 —, or —CH 2 —, and where R 1  is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       where R 2  in formula (3) is a divalent organic group that is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       where R 3  is independently —CH 3 , —Cl, —Br, —F, or —CH 3 O. 
     
     
       2. A polyimide film according to  claim 1 , further comprising a repeating unit of formula (2) below in its molecules 
       
         
           
           
               
               
           
         
       
       where R is the same as that of the formula (1), and R 2  is the same as that of the formula (3). 
     
     
       3. A polyimide film according to  claim 1 , further comprising a repeating unit of formula (4) below in its molecules 
       
         
           
           
               
               
           
         
       
       where R 4  is a divalant organic group selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
       4. A polyimide film according to  claim 1 , further comprising a repeating unit of formula (5) below in its molecules 
       
         
           
           
               
               
           
         
       
       where R 5  is a at least two kinds selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       and R 4  is a divalent organic group that is represented by 
       
         
           
           
               
               
           
         
       
     
     
       5. A polyimide film according to  claim 1 , further comprising repeating units of formulae (6), (7), (8), and (9) below in its molecules 
       
         
           
           
               
               
           
         
       
     
     
       6. A producing process of a flexible printed circuit board, comprising the step of stamping a polyimide film with a tear propagation resistance variation of not more than 1.0 g, and not less than 25 mol % of paraphenylene diamine and not less than 25 mol % of 4,4-diaminodiphenylether, both as diamine components, with respect to a total diamine component, said polyimide film comprising a repeating unit of formula (1) below in its molecules 
       
         
           
           
               
               
           
         
       
       where R is 
       
         
           
           
               
               
           
         
       
       and where n of the group R is an integer of 1 to 3, X and Y are independently a hydrogen, a halogen, a carboxyl group, a lower alkyl group with no greater than 6 carbon atoms, or a lower alkoxy group with no greater than 6 carbon atoms, and A is —O—, —S—, —CO—, —SO 2 —, or —CH 2 —, and where R 1  is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       where R 2  in formula (3) is a divalent organic group that is selected from the group consisting of 
       
         
           
           
               
               
           
         
       
       where R 3  is independently —CH 3 , —Cl, —Br, —F, or —CH 3 O.